Soaking pit and burner arrangement



March 17, 1970 R. KNAAK ET AL SOAKING PIT AND BURNER ARRANGEMENT Filed May 28, 1968 Fig. 1

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United States Patent SOAKING PIT AND BURNER ARRANGEMENT Riidiger Knaak, Neuss, Giinter Hepp, Oberhausen, Lothar I-Iartwig, Essen, and Hans Christoph Pohl, Norf, near Neuss, Germany, assignors to Koppers-Wistra-Ofenbau G.m.b.H., Dusseldorf-Heerdt, Germany Filed May 28, 1968, Ser. No. 732,701

Claims priority, application Germany, June 15, 1967,

Int. Cl. F23c 5/00 US. Cl. 263-40 14 Claims ABSTRACT OF THE DISCLOSURE A soaking pit wherein the primary burner or burners are installed in a first end wall and discharge hot gases at a level above the charge toward a second end wall which deflects hot gases toward one or more evacuating openings provided in the first end wall at a level below the primary burners. The second end wall supports one or more secondary burners which are started when the primary burners operate at less than maximum capacity and discharge hot gases toward the evacuating opening.

BACKGROUND OF THE INVENTION The present invention relates to metallurgical furnaces in general, and more particularly to improvements in soaking pits for ingots. Still more particularly, the invention relates to improvements in soaking pits of the type wherein one or more primary burners discharge hot gases into an enclosure for the charge at a level above the charge and wherein such gases. are deflected by a furnace wall and are evacuated through one or more openings located at a level below the primary burners.

When the ingots in a soaking pit are being heated to the temperature required for rolling, the primary burner or burners operate at full capacity. Hot gases issuing from the primary burners flow along the heads of ingots toward a wall at the opposite end of the enclosure which accommodates the charge. The wall deflects the gases so that such gases flow along the lower portions of ingots and are withdrawn through one or more evacuating openings provided in that wall which supports the primary burners. This insures substantially uniform heating of all zones of the ingots. When the ingots are heated to requisite rolling temperature, the heating action of primary burners is reduced so that the enclosure for the charge receives only so much heat as is necessary to maintain the ingots at the rolling temperature. In other words, the quantity of hot gases and the speed at which such gases issue from the primary burners are reduced considerably when the charge is already heated to requisite temperature. Consequently, hot gases which issue from the primary burners are often deflected midway between the walls of the enclosure and are evacuated by way of the discharge opening so that the temperature of ingots which are remote from the primary burners drops appreciably, especially in the lower portions of such remote ingots. Therefore, the partially or completely cooled ingots are unfit for rolling without renewed heating.

SUMMARY OF THE INVENTION It is an object of our invention to provide a soaking pit wherein the ingots can be maintained at a requisite temperature even at the time when the primary burner or burners operate at less than full capacity.

Another object of the invention is to provide a soaking pit wherein all ingots, even those which are remote from the primary burner or burners, can be maintained at a requisite temperature for shorter or longer intervals of time before the heating action of the primary burners is reduced.

A further object of the invention is to provide simple, compact and reliable auxiliary or secondary heating means for charges in soaking pits and to construct, assemble and mount the secondary heating means in such a way that it can properly heat all those components of a charge which cannot be heated to or maintained at a requisite temperature by primary burners when the primary burners are operated at less than maximum capacity.

Still another object of the invention is to provide auxiliary or secondary heating means which can be installed in presently known soaking pits.

The improved soaking pit comprises wall means defining an enclosure having a lower portion which can accommodate a charge consisting of one or more rows of or otherwise distributed ingots, the wall means including first and second wall members flanking the enclosure from opposite sides, primary heating means preferably including one or more primary burners installed in or in the region of the first wall member to discharge hot gases into the enclosure substantially above the lower portion thereof and toward the second wall member so that such gases heat the heads of ingots and are deflected by the second wall member to flow along the lower portions of ingots and to be withdrawn by way of one or more evacuating openings or channels provided in the first wall member in a zone below the primary burners, and secondary heating means provided in or in the region of the second wall member to discharge hot gases toward the first wall member, preferably in such a way that gases issuing therefrom flow along the lower portions of ingots and in the same direction as gases which are deflected by the second wall member when the primary burners operate at full capacity. The secondary heating means is preferably started when the primary heating means operates at a reduced capacity.

In accordance with another feature of our invention, the soaking pit is preferably provided with a barrier which prevents splashing of molten material against the secondary heating means. Such molten material normally accumulates above the bottom wall of the soaking pit. The barrier may include a niche in the wall member which accommodates the secondary heating means or a step or the like provided in the lower portion of the enclosure between the outlet or outlets of the secondary heating means and the pool of molten material.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved soaking pit itself, how.- ever, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a central longitudinal vertical sectional view of a soaking pit which embodies one form of our invention;

FIG. 2 is a transverse vertical sectional view of the soaking pit as seen in the direction of arrows from the line IIII of FIG. 1;

FIG. 3 is a horizontal sectional view as seen in the direction of arrows from the line III-III of FIG. 1; and

FIG. 4 is a similar horizontal sectional view of a modified soaking pit.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring first to FIGS. 1 to 3, there is shown a soaking pit which comprises a wall structure defining an enclosure E for a charge of ingots 8 and including two end wall members 2, 3 flanking the enclosure E from opposite sides. The charge of ingots 8 is accommodated in the lower portion of the enclosure E, i.e., the ingots rest on a bottom wall 7.

The primary heating means includes a burner 1 which discharges hot gases in the direction indicated by arrow A so that such gases flow along and around the heads of ingots 8 and are deflected by the wall member 3 to flow toward the wall member 2 and to be withdrawn through one or more evacuating openings or channels 4. The channel or channels 4 are provided in the wall member 2 at a level below the primary burner 1 so that hot gases which are deflected by the wall member 3 heat the lower portions of ingots 8.

In accordance with a feature of our invention, the wall member 3 supports at least one secondary heating means including a high-speed burner 5 which discharges hot gases at a high speed into the stream of hot gases deflected by the internal surface of the wall member 3 and flowing toward the evacuating channel 4. The axis 5a of the secondary burner 5 is inclined with reference to a horizontal plane, preferably by an angle of between 15 and 25 degrees. The secondary burner 5 is started when the ingots 8 are heated to requisite rolling temperature, i.e., when the primary burner 1 operates at less than maximum or normal capacity and the speed of gases issuing therefrom is reduced considerably so that such gases might not reach the wall member 3 but are likely to be deflected by draft in the channel 4 when they reach an intermediate portion of the enclosure E.

The barrier of the soaking pit shown in FIGS. 1 to 3 includes a simple step or stair 6 which is adjacent to the lowermost part of the wall member 3 and extends above the bottom wall member 7 so that it prevents molten material which accumulates on the wall member 7 from splashing into the outlet of the secondary burner 5 when the ingots are carelessly introduced into the enclosure E. Such molten material consists of slag and scale. The height of the step 6 is selected in such a way that it invariably exceeds the maximum depth of molten material above the bottom wall member 7. Alternatively, the barrier may comprise a niche provided in the wall member 3 to accommodate the secondary burner 5 and to prevent splashing of molten material into the outlet of such burner.

As shown in FIG. 3, the charge in the lower portion of the enclosure E comprises two rows of upright ingots 8 which define between themselves a passage or gap 9 extending between the wall members 2, 3 in line with the channel 4, primary burner 1 and secondary burner 5. The secondary burner discharges hot gases into this gap 9 so that the ingots 8 cannot deflect such gases on their way toward the channel 4.

FIG. 4 shows a second soaking pit wherein the wall member 3' accommodates two secondary burners 5 preferably located at the same level and each in line with one of two gaps 9 formed by three rows of ingots 8 in the enclosure E'. The number of gaps and the number of secondary burners may exceed two. The secondary burner or burners insure satisfactory heating of those ingots which are remote from the end wall member 2, i.e., which could not be properly heated or maintained at a requisite temperature when the primary burner 1 operates at less than normal capacity.

Hot gases issuing from the secondary burner or burners suck hot gases which issue from the primary burner and thus insure that gases discharged by the primary burner invariably advance all the way to or at least close to the wall member 3 or 3'. Such sucking action is due to the high speed of gases which are discharged by the secondary burner or burners. In other words, the secondary burner or burners insure that the manner in which gases issuing from the primary burner circulate in the enclosure E or E does not change when the heating action of the primary burner is reduced in order to avoid overheating of ingots.

Since the primary purpose of the secondary burner or burners is to insure satisfactory circulation of gases which issue from the primary burner 1, the heating action of gases issuing from the burner 5 or burners 5' is of secondary importance.

Such mounting of the burner 5, or burners 5' that the burner axis is inclined downwardly and inwardly with reference to a horizontal plane is of advantage because gases issuing from the outlets of secondary burners draw the gases coming from the primary burner toward the lower portions of the ingots. Excessive inclination of secondary burners is not desirable at the present time because hot gases issuing from strongly inclined secondary burners could cause overheating and premature destruction of the bottom wall member 7. The lowest level of the outlet of each secondary burner is determined by the maximum depth of the pool of molten material which accumulates on the bottom wall member 7. The aforementioned barrier is normally provided to protect the secondary burners against damage by contact with molten material when the ingots are dropped into the enclosure E or E so that they cause splashing. If the barrier includes a niche in the wall member 3 or 3', the configuration of surfaces surrounding the niche must be selected in such a way that they do not interfere with the desirable effect of hot gases which issue from the secondary burner or burners. If the barrier comprises a step, such as the step 6 shown in FIG. 1, one group of ingots 8 can be placed onto the step. Molten slag flows off the ingots resting on the step 6 so that it cannot splash into the outlet of the secondary burner 5.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of our contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

Whta is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

We claim:

1. In a metallurgical furnace, particularly in a soaking pit, a combination comprising wall means defining an enclosure having a portion for reception of a charge, said wall means including first and second wall members flanking said enclosure from opposite sides; primary heating means provided in the region of said first wall member for discharging hot gases into said enclosure above said portion thereof and toward said second wall member; evacuating means provided in said first wall member at a level below said primary heating means; secondary heating means provided in the region of said second wall member for discharging hot gases toward said first wall member at a level located below the level of the hot gases discharged by said primary heating means into said enclosure.

2. A combination as defined in claim 1, wherein said secondary heating means is arranged to discharge hot gases into said portion of said enclosure.

3. A combination as defined in claim 1, wherein gases discharged by said primary heating means are deflected by said second wall member toward said evacuating means and wherein said secondary heating means is arranged to discharge hot gases into the thus deflected gases in the general direction of said evacuating means.

4. A combination as defined in claim 1, wherein each of said heating means comprises at least one burner.

5. A combination as defined in claim 4, wherein the axis of the burner in said secondary heating means is inclined with reference to a horizontal plane.

6. A combination as defined in claim 5, wherein the axis of said last mentioned burner is inclined downwardly as considered in the direction of gas discharge therefrom, and wherein the inclination of said axis with reference to said horizontal plant is in the range of between 15 and 25 degrees.

7. A combination as defined in claim 1, further comprising a protective barrier for said secondary heating means.

8. A combination as defined in claim 7, wherein said wall means further includes a bottom wall member extending between said first and second wall members and wherein a supply of molten material normally accumulates above said bottom wall member when the furnace is in use, said barrier being arranged to prevent splashing of molten material against the secondary heating means.

9. A combination as defined in claim 8, wherein said secondary heating means comprises at least one highvelocity burner and wherein said barrier comprises a niche provided in said second wall member for said burner.

10. A combination as defined in claim 8, wherein said secondary heating means comprises a high-velocity burner mounted in said second wall member and said barrier comprises a step provided in said portion of said enclosure between the outlet of said burner and said bottom wall member.

11. A combination as defined in claim 1, wherein said portion of said enclosure is arranged to accommodate a charge including several ingots defining at least one passage extending between said wall members, said secondary heating means comprising a burner mounted in said second wall member and having an outlet arranged to discharge hot gases into the passage.

12. A combination as defined in claim 11, wherein the ingots of the charge in said portion of said enclosure define several passages and said secondary heating means comprises several burners each of which discharges hot gases into one of said passages.

13. A combination as defined in claim 1, wherein said secondary heating means comprises at least one highvelocity burner.

14. A combination as defined in claim 13, wherein said high-Velocity burner is arranged for discharging a stream of hot gases below the hot gases emanating from said primary heating means and in the general direction towards said evacuating means during reduction of the speed of the hot gases emanating from said primary heating means to prevent during such reduction change of circulation of the hot gases emanating from said primary I heating means in said enclosure.

References Cited UNITED STATES PATENTS 2,297,696 10/1942 Elder et al. 263-43 2,849,221 8/1958 Cone et al. 263-43 3,002,736 10/ 1961 Travis 263-52 JOHN J. CAMBY, Primary Examiner 

